Surface plasmon resonance sensor based on an array of diffraction gratings for highly parallelized observation of biomolecular interactions

We report a novel surface plasmon resonance (SPR) sensor for highly parallelized biomolecular interaction analysis (BIA). This sensor utilizes an array detection format and angular spectroscopy of surface plasmons on a two-dimensional array of metallic diffraction gratings. Each diffraction grating on a sensor chip serves both as an SPR coupler and a sensing channel in which refractive index changes induced by biomolecular interaction events are measured. We theoretically optimized the diffraction grating-based sensor to yield maximum resolution in the measurement of refractive index changes. Based on this study, we developed a prototype sensor instrument which enables parallel measurements with high-refractive index resolution (5 × 10−7 RIU) in large number of sensing channels (120). The instrument consists of a two-dimensional array of sensing channels on a sensor chip, a fluidic system for sample delivery, and an SPR optical readout system. By using this instrument and micro spotting to produce a chip array, we evaluated the cross-binding of antibodies against a selected set of endocrine-disrupting compounds (atrazine, 2,4-dichlorophenoxyaceic acid, 4-nonylphenol and benzo[a]pyrene) to respective protein–analyte conjugates.